CVE-2009-3129VulnerabilityPublished 03/03/2022Updated 10/24/2026

CVE-2009-3129: Microsoft Excel Featheader Record Memory Corruption Vulnerability

Affects Microsoft ExcelSource CISA KEV

Severity

High

No CVSS score published yet

Exploitation: Actively exploited – in CISA KEV since 03/03/2022
KEV deadline: 03/24/2022
EPSS: 84.0% chance of exploitation in 30 days – higher than 99% of CVEs

What to do

CISA required action

Apply updates per vendor instructions.

nvd.nist.gov/vuln/detail/CVE-2009-3129 (opens in a new tab)

Description

A vulnerability in Microsoft Excel involving the FEATHEADER record allows remote attackers to execute arbitrary code by crafting a spreadsheet with an invalid cbHdrData size element that corrupts memory via a pointer offset. This vulnerability has been exploited in the wild.

Summary

CVE-2009-3129 is a memory corruption vulnerability in Microsoft Office Excel. It occurs when Excel processes a spreadsheet containing a FEATHEADER record with an invalid cbHdrData size element, which affects a pointer offset and enables remote code execution. The vulnerability has been exploited in the wild, indicating active use by attackers. No specific affected versions or patch information are provided in the input data.

Impact

Successful exploitation allows remote attackers to execute arbitrary code on the affected system, potentially leading to full system compromise. The vulnerability has been observed in active exploitation campaigns, increasing its risk.

Mitigation

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no patch or official fix information is provided, users should monitor Microsoft advisories for updates and avoid opening untrusted Excel files containing suspicious FEATHEADER records.

Weaknesses

CWE-94Code Injection (opens in a new tab)

What to do

Description

AnalysisAI-generated, updated 10/24/2026, 10:12:16 UTC

Weaknesses

References

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